No nuclear back-up for Germany

31 August 2011

A nuclear reactor will not be kept on standby for Germany's winter months, the network agency has decided. Threats to grid stability are real, it said, but more fossil fuel and grid improvements should ensure power supplies.

The Bundesnetzagentur is a separate authority within the Ministry of Economics and Technology with responsibility to develop electricity, gas, rail and telecoms networks and protect these services for the public. A clause in the latest version of the Nuclear Exit Law gave it the right to request a nuclear reactor to stand ready to restart should Germany's grid be destabilised by weather and demand conditions. The agency had until 1 September to make up its mind on this and today announced it would not impose the condition on any of the country's four nuclear utilities.

The issue arose because of the immediate shutdown of eight reactors by order of Angela Merkel's government in March and the legislation that made this permanent in July. The moves left Germany with "only just adequate" power generation capacity, very little in reserve for times of high demand and a deficit of about 1000 MWe in the south west - as well as strained north-south and east-west connections.

The shutdown of eight reactors made Germany a net power importer (Image: Bundesnetzagentur; Data: ENTSO-E)

Transmission grids were taken "to the edge of their resilience," said the agency in May, noting "the risk of non-controllable network disturbances is increasing distinctly." It said that some maintenance work on the grid has had to be postponed because certain systems are now indispensable, but "to a certain degree, delay of service and maintenance works can be managed."

Power imports stepped up from the moment the eight reactors closed and the Bundesnetzagentur grew concerned that conditions of high demand and low wind "as is typical on a frosty calm winter evening" would result in an overstretch of north-south connections. Conversely, times of high wind could cause low-voltage problems that would jeopardise supplies in Hamburg and the greater Frankfurt area.

Even before the nuclear shutdown, the north-south Paffendorf line experienced overloads of up to 125%, said the agency. Should there be sudden failure of a power plant or grid node, "a line load in excess of 140% would occur which would be uncontrollable due to cascading automatic tripping of protective devices."

These and other scenarios for instability "while extreme, are not so unlikely" said the agency, which had identified a reserve capacity of 1400-2000 MWe as required in the south of the country to start at short notice. Instead the agency said today it will try to accelerate the construction of power lines and keep operating reserve capacity on hand at the 2000 MWe coal and gas-fired Staudinger power plant.

This loss of low-carbon nuclear power, the consequent move to rely more on fossil fuel and the forced return to central planning is "dubious in terms of energy economics, economically inefficient and ecologically harmful, but must be accepted for a transitional period and is unavoidable at the moment," said the agency.

One "urgent need" for the near term is a 100 kilometre high-voltage line from Hamburg to Schwerin, presumably navigating around the 470 square kilometre national park that lies between. Another is the on-schedule start-up of four new fossil units by the end of 2012 to secure power for national railway operator Deutsche Bahn. Not completing these units on time would mean more stress on overburdened north-south connectors.